What are the accuracy requirements for servo motor bearings and how to adjust them?

The accuracy requirements for servo motor bearings are critical due to their direct impact on the precision and performance of the servo motor. These requirements typically focus on factors such as bearing runout, rigidity, vibration levels, and thermal stability. Here’s an overview of these requirements and how to adjust them.

Servo Motor Bearings Accuracy Requirements

Runout Accuracy

  • Radial Runout: This refers to the deviation in the radial direction when the bearing is rotated. High precision applications demand minimal radial runout.
  • Axial Runout: Similar to radial runout but in the axial direction. Critical for maintaining positional accuracy along the axis of rotation.


  • Servo motors often require bearings that can handle high loads without significant deformation to ensure precise movement and responsiveness.

Vibration Levels

  • Low vibration levels are essential to prevent any adverse effects on the motor’s accuracy and to ensure smooth operation.

Thermal Stability

  • Bearings should maintain performance under varying temperatures, as thermal expansion can affect accuracy.

Adjusting Bearings for Servo Motors

Proper Installation

  • Ensure the bearing is properly seated and aligned during installation. Misalignment can lead to increased runout and reduced accuracy.
  • Use precise mounting techniques to avoid any deformation of the bearing rings.

Preload Adjustment

  • Adjusting the preload can help achieve the desired rigidity and reduce play in the bearings. Too much preload can increase friction and wear, while too little can cause excessive play and vibration.
  • Preload can be applied using spring mechanisms, spacers, or controlled axial force during assembly.

Balancing the Rotating Assembly

  • Balance the rotor and the bearing assembly to reduce vibrations. Imbalances can lead to increased vibration levels and reduced accuracy.


  • Use the correct type and amount of lubrication. Over-lubrication can cause excess drag, while under-lubrication can lead to increased wear and noise.

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